Facile synthesis of natural stearic acid modified carbon adsorbent for toluene adsorption under high humidity conditions

Abstract

The diminished adsorption efficiency of porous carbon for volatile organic compounds (VOCs) in high-humidity conditions poses a critical challenge that limits its widespread application. This study presents a facile method for enhancing the adsorption capacity of coffee grounds activated carbon in high-humidity environments through stearic acid modification. The incorporation of 20 % stearic acid (20 % ST-AC) significantly amplifies the saturated adsorption capacity and penetration duration of porous carbon for toluene under high-humidity conditions. Specifically, the toluene adsorption capacity improves from 230 mg/g to 498 mg/g in an 80 % relative humidity condition. However, increasing the stearic acid doping ratio beyond 20 % has a limited impact on moisture resistance while leading to micropore blockage, resulting in a significant reduction in toluene adsorption capacity. Additionally, 20 % ST-AC demonstrates excellent adsorption recycling performance over five cycles, maintaining 97 % of its original adsorption capacity. This study provides a novel perspective on the preparation of hydrophobic activated carbon, which helps to address the challenge of VOC adsorption in high-humidity flue gas environments.